A communication-free adaptive virtual inertia control of cascaded-type VSGs for power oscillation suppression

This work introduces a communication-free adaptive virtual inertia control to realize the power oscillation suppression of cascaded-type virtual synchronous generators (VSGs). The frequency of the transmission line current is the common information in the cascaded structure. When the frequency of distributed generators (DGs) deviates from the frequency of transmission line current, larger inertia is added to impede deviations. On the contrary, when frequencies of DGs come close to the frequency of transmission line current, smaller inertia is applied to accelerate the convergence of systems. The proposed control strategy can make all DGs frequency align to the line current frequency quickly. Thus, the power oscillations are damped. Further, the proposed scheme is constructed only based on the local information of DGs. Therefore, it is a fully communication-free manner, and the system holds commendable reliability. The stability of the system is proved with the pro-posed control method. Finally, the effectiveness of the proposed control strategy has been validated by simu-lations and experiments.